1. Field of the Invention
The present invention relates to a magneto-resistive element, a magnetic head, and a magnetic recording and reproduction apparatus used for magnetic recording or magneto-optic recording, and more specifically to a magneto-resistive element, a magnetic head, and a magnetic recording and reproduction apparatus using a magnetic substrate.
2. Description of the Related Art
Recently, an increase in image information used for digital broadcasting or the like requires a further improvement in the magnetic recording density. Specifically in the field of magnetic heads for use with a magnetic tape, an MIG (metal in gap) head, using a metal magnetic film having a high saturation magnetic flux density in the vicinity of the magnetic gap, is being used more and more widely.
The transfer rate for information recording is now required to be almost 100 MHz. Inductive magnetic heads including an MIG head have a problem that the reproduction capability is significantly reduced as the frequency is increased, due to the loss of eddy current and the limit of ferromagnetic resonance.
In order to overcome this problem, a yoke-type thin film magnetic head using a GMR (gigantic magneto-resistive) element is now under study. The yoke-type thin film magnetic head includes a yoke formed of a high saturation magnetic flux density material and thus has an advantage of a smaller loss at a high frequency.
However, a magnetic head using a thin film magnetic material has a problem of a significantly poor anti-abrasion characteristic when used for a tape medium. The poor anti-abrasion characteristic affects the life of the head.
A head including a yoke formed of a high saturation magnetic flux density material and including a GMR element as a magneto-resistive element has the following problem. A free layer of the GMR element located in a gap in the yoke has a thickness of several nanometers, and thus magnetic saturation is likely to occur. Therefore, a magnetic circuit formed of the yoke has a larger magnetic resistance, and as a result, the efficiency of the head is reduced.
According to one aspect of the invention, a magneto-resistive element includes a magnetic substrate; a magnetic layer; and a non-magnetic layer provided between the magnetic substrate and the magnetic layer.
In one embodiment of the invention, a relative angle between a magnetization direction of the magnetic substrate and a magnetization direction of the magnetic layer changes in accordance with a change in an external magnetic field.
In one embodiment of the invention, the magnetic substrate includes a free layer in which magnetization rotation with respect to an external magnetic field is possible. The magnetic layer includes a fixed layer in which magnetization rotation with respect to the external magnetic field is more difficult to occur than in the free layer.
In one embodiment of the invention, the magneto-resistive element further includes a hard magnetic layer with a large coercive force provided so as to face the magnetic substrate with the magnetic layer interposed therebetween.
In one embodiment of the invention, the magneto-resistive element further includes an anti-ferromagnetic layer provided so as to face the magnetic substrate with the magnetic layer interposed therebetween.
In one embodiment of the invention, the magneto-resistive element further includes a synthetic anti-ferromagnetic layer provided so as to face the magnetic substrate with the magnetic layer interposed therebetween, the synthetic anti-ferromagnetic layer being magnetically coupled with the anti-ferromagnetic layer.
In one embodiment of the invention, the magneto-resistive element further includes a soft magnetic layer with a high saturation magnetic flux density provided between the magnetic substrate and the non-magnetic layer.
In one embodiment of the invention, the magneto-resistive element further includes an anti-ferromagnetic layer provided between the magnetic substrate and the non-magnetic layer.
In one embodiment of the invention, the magnetic substrate contains ferrite.
In one embodiment of the invention, the magnetic substrate contains an oxide.
In one embodiment of the invention, the magnetic substrate contains a single crystalline oxide.
In one embodiment of the invention, the magnetic layer contains magnetite.
In one embodiment of the invention, the magnetic layer contains at least one element selected from the group consisting of O, N, P, C and B.
In one embodiment of the invention, the non-magnetic layer includes a tunnel layer.
In one embodiment of the invention, the non-magnetic layer includes a metal non-magnetic layer.
According to another aspect of the invention, a magneto-resistive element includes a magnetic substrate; a first magnetic layer; a second magnetic layer provided so as to face the magnetic substrate with the first magnetic layer interposed therebetween; and a first non-magnetic layer provided between the first magnetic layer and the second magnetic layer.
In one embodiment of the invention, a relative angle between a magnetization direction of the first magnetic layer and a magnetization direction of the second magnetic layer changes in accordance with a change in an external magnetic field.
In one embodiment of the invention, the magnetic substrate and the first magnetic layer are magnetically coupled with each other.
In one embodiment of the invention, the magnetic substrate and the first magnetic layer are coupled with each other by ferromagnetic coupling by which a magnetization direction of the magnetic substrate and a magnetization direction of the first magnetic layer are parallel to each other.
In one embodiment of the invention, the magnetic substrate and the first magnetic layer are coupled with each other by ferromagnetic coupling by which a magnetization direction of the magnetic substrate and a magnetization direction of the first magnetic layer are anti-parallel to each other.
In one embodiment of the invention, the magnetic substrate and the first magnetic layer are coupled with each other by static magnetic coupling.
In one embodiment of the invention, the magneto-resistive element further includes an underlying layer provided between the magnetic substrate and the first magnetic layer.
In one embodiment of the invention, the underlying layer includes a second non-magnetic layer.
In one embodiment of the invention, the underlying layer includes an anti-ferromagnetic layer.
In one embodiment of the invention, the underlying layer has a thickness in the range of 0.5 nm to 50 nm including 0.5 nm and 50 nm.
In one embodiment of the invention, the first magnetic layer includes a free layer in which magnetization rotation with respect to an external magnetic field is possible. The second magnetic layer includes a fixed layer in which magnetization rotation with respect to the external magnetic field is more difficult to occur than in the free layer.
In one embodiment of the invention, the magneto-resistive element further includes a hard magnetic layer with a large coercive force provided so as to face the magnetic substrate with the second magnetic layer interposed therebetween.
In one embodiment of the invention, the magneto-resistive element further includes an anti-ferromagnetic layer provided so as to face the magnetic substrate with the second magnetic layer interposed therebetween.
In one embodiment of the invention, the magneto-resistive element further includes a synthetic anti-ferromagnetic layer provided so as to face the magnetic substrate with the second magnetic layer interposed therebetween, the synthetic anti-ferromagnetic layer being magnetically coupled with the anti-ferromagnetic layer.
In one embodiment of the invention, the magneto-resistive element further includes a soft magnetic layer with a high saturation magnetic flux density provided between the magnetic substrate and the first magnetic layer.
In one embodiment of the invention, the magnetic substrate contains ferrite.
In one embodiment of the invention, the magnetic substrate contains an oxide.
In one embodiment of the invention, the magnetic substrate contains a single crystalline oxide.
In one embodiment of the invention, the first magnetic layer contains magnetite.
In one embodiment of the invention, the first magnetic layer contains at least one element selected from the group consisting of O, N, P, C and B.
In one embodiment of the invention, the first non-magnetic layer includes a tunnel layer.
In one embodiment of the invention, the first non-magnetic layer includes a metal non-magnetic layer.
In one embodiment of the invention, the magneto-resistive element further includes a flux guide provided so as to face the magnetic substrate with the second magnetic layer interposed therebetween.
In one embodiment of the invention, the magneto-resistive element further includes a non-magnetic conductive layer provided so as to face the magnetic substrate with the flux guide interposed therebetween.
In one embodiment of the invention, the first magnetic layer includes a magnetic layer with a high spin polarization.
In one embodiment of the invention, the first magnetic layer further includes a non-magnetic layer for anti-ferromagnetic exchange coupling.
In one embodiment of the invention, the first magnetic layer further includes a magnetic layer for anti-ferromagnetic exchange coupling provided so as to face the magnetic layer with a high spin polarization with the non-magnetic layer for anti-ferromagnetic exchange coupling interposed therebetween.
In one embodiment of the invention, the first magnetic layer further includes an anti-ferromagnetic layer provided so as to face the non-magnetic layer for anti-ferromagnetic exchange coupling with the magnetic layer for anti-ferromagnetic exchange coupling interposed therebetween.
According to still another aspect of the invention, a magnetic head includes a magneto-resistive element including a magnetic substrate, a magnetic layer, and a non-magnetic layer provided between the magnetic substrate and the magnetic layer; and also includes a yoke. The yoke has a magnetic gap formed of a non-magnetic material. The magnetic substrate acts as a portion of the yoke.
In one embodiment of the invention, the yoke includes a magnetic member having a saturation magnetic flux density higher than a saturation magnetic flux density of the magnetic substrate at least in the vicinity of the magnetic gap, the magnetic head further comprising an electromagnetic coil wound around the yoke.
According to still another aspect of the invention, a magnetic head includes a magneto-resistive element including a magnetic substrate, a first magnetic layer, a second magnetic layer provided so as to face the magnetic substrate with the first magnetic layer interposed therebetween, and a first non-magnetic layer provided between the first magnetic layer and the second magnetic layer; and also includes a yoke. The yoke has a magnetic gap formed of a non-magnetic material. The magnetic substrate acts as a portion of the yoke.
In one embodiment of the invention, the yoke includes a magnetic member having a saturation magnetic flux density higher than a saturation magnetic flux density of the magnetic substrate at least in the vicinity of the magnetic gap, the magnetic head further comprising an electromagnetic coil wound around the yoke.
According to still another aspect of the invention, a magnetic recording and reproduction apparatus includes one of the above-described magnetic head for reproducing data from a recording medium so as to generate a signal and for recording data represented by a signal on the recording medium; an arm for mounting the magnetic head; a driving section for driving the arm; and a signal processing section for processing the signal. The recording medium is surface-treated with a DLC film.
In one embodiment of the invention, the yoke has a surface facing the recording medium, and the surface is surface-treated with a DLC film.
According to still another aspect of the invention, a magnetic recording and reproduction apparatus includes any of the above-described magnetic heads; a rotatable drum for mounting the magnetic head on an external circumferential surface thereof; and a tape guiding mechanism for guiding the magnetic tape to the rotatable drum so as to place the magnetic tape into contact with the external circumferential surface. The magnetic head records data on and reproduce data from the magnetic tape.
In one embodiment of the invention, the yoke has a surface facing the magnetic tape, and the surface is surface-treated with a DLC film.
The present invention provides the following effects.
A magneto-resistive element utilizing the soft magnetic characteristics of the magnetic substrate is provided.
In the case where the magnetic substrate contains, for example, an oxide, magnetite is unlikely to diffused to, for example, the magnetic substrate.
In the case where the magnetic substrate contains, for example, a single crystalline oxide, epitaxial growth of the layers is realized.
In the case where the magnetic layer contains at least one element selected from the group consisting of O, N, P, C and B, especially when the magnetic substrate contains an oxide, reaction deteriorating magnetic characteristics, for example, interdiffusion, are suppressed.
In the case where the magneto-resistive element includes a non-magnetic layer having a tunnel layer and thus utilizes a tunneling magnetic effect, even when the magnetic substrate is conductive, the MR (magnetic resistance) is not lowered by the shunt effect, unlike the conventional GMR element. A tunneling magnetic effect element utilizing the magnetic characteristics of the magnetic substrate can be provided.
In the case where the magneto-resistive element includes a non-magnetic layer including a metal non-magnetic layer and thus utilizes a GMR effect, and further when, for example, the magnetic substrate is highly resistive, the MR is not lowered by the shunt effect. A GMR element utilizing the magnetic characteristics of the magnetic substrate can be provided.
Since the yoke includes a magnetic substrate having superb magnetic characteristics, the magnetic head has superior anti-abrasion characteristics which is inherent in the magnetic substrate.
Since the soft magnetic layer with a high saturation magnetic flux density is provided in the vicinity of the magnetic gap of the yoke (recording gap), data can be recorded on a magnetic recording medium in a magnetic field for recording generated by the magnetic coil. In addition, the magnetic head has excellent anti-abrasion characteristics due to a magneto-resistive element having satisfactory reproduction characteristics.
In a magnetic recording and reproduction apparatus according to the present invention, the DLC film for increasing the resistance of the magnetic head so as to prevent the leak current from flowing to the magnetic recording and reproduction apparatus, specifically, the magnetic head. Therefore, reduction in the magneto-resistive effect caused by the leak current is suppressed.
Thus, the invention described herein makes possible the advantages of providing a magneto-resistive element, a magnetic head, and a magnetic recording and reproduction apparatus having a satisfactory anti-abrasion characteristic and a sufficiently high head efficiency.